Airports presently use carousel style conveyors for both baggage claim and sortation operations. A series of overlapping plates or pallets overlie the chain and are supported by it for movement along the top of a supporting frame. See for example U.S. Pat. Nos. 4,650,066 and 4,476,974. Sortation (make-up, racetrack) carousel operations are different from claim (baggage reclaim carousel) operations. Sortation carousels often operate 18 to 20 hours per day. Claim carousels only operate intermittently, during baggage reclaim operations, until a predetermined time-out is reached. Known designs for such carousels typically rely on a single large drive unit that engages a drive chain. Multiple drives for a single conveyor have been deployed when additional power was needed due to the length of the carousel path and/or the expected weight of objects transported. However, in such known systems, no attempt has been made to control the multiple drive units in something other than by means of basic on/off pushbutton controls.
Carousel conveyors currently in use are generally reliable but require large expensive drive systems that waste energy and result in downtime when there is a problem with the drive assembly that requires repair or maintenance. Based on current standards for carousel drive design, the redundancy requirements (that insure system availability) result in excessive HP capacity and energy consumption. A need persists for a carousel conveyor suitable for airport sues uses that has a longer life, consumes less energy, and can be controlled in a manner that responds to the load, rather than in a simple on-off mode. The present invention addresses these needs.